锅炉蒸汽吹灰、声波吹灰和燃气高能脉冲吹灰的技术经济比较

锅炉及热交换器的积灰、结焦使锅炉排烟温度上升，导致热效率下降，并会引起受热面腐蚀，影响经济性、安全性。故长期以来，人们一直在寻求较好的除灰方式。通过对目前主要采用的蒸汽吹灰、声波吹灰及燃气高能脉冲吹灰的原理、效果、费用比较，认为燃气高能脉冲吹灰值得推广应用。     

燃气脉冲吹灰装置在焦结炉余热锅炉上的应用

介绍火法锌冶炼焦结炉余热锅炉的积灰部位，并分析积灰的成因。简述燃气脉冲吹灰装置的作用机理，总结了燃气脉冲吹灰装置在焦结炉余热锅炉上的应用效果。     

脉冲燃气吹灰器

利用高温、高压燃气以极高的速度和巨大声能从定向喷嘴射向锅炉换热器管束表面积灰，使其脱落．达到吹灰目的。喷口近处被打掉的灰块获得一定动能后又去打掉较远处的积灰。随着脉冲吹灰次数的增加．吹灰范围不断扩大。     

FW余热锅炉吹灰系统改造

采用KMY--GH型冲击波(高能脉冲)吹灰器替代FW余热锅炉对流区原有的弹簧振打锤,解决余热锅炉对流换热区积灰清理问题.然而,该冲击波吹灰器的除灰效果并不理想,通过对吹灰系统一系列的改造,增强了冲击波吹灰器的出灰效果,实现了锅炉的在线清灰,保证了系统设备长期稳定运行.     

燃气冲击波吹灰技术及其应用

介绍了一种实用新型的锅炉吹灰技术——燃气冲击波吹灰器的吹灰系统构成及工作原理，论述了该技术的可行性和安全性及其在循环流化床锅炉的应用情况，并将该技术与其他现有常用的吹灰技术作了技术经济指标上的对比分析。     

燃气脉冲吹灰技术及其在大型锅炉上的应用

针对蒸汽吹灰和声波吹灰技术存在的问题,开发了燃气脉冲吹灰技术,10年前首次应用于600 MW锅炉机组回转式空气预热器上.经过不断改进,现已成功地应用到300～600 MW锅炉机组水平烟道、尾部烟道中的各类对流受热面吹灰上,表现出其独特的机理和效果.     

循环流化床锅炉脉冲吹灰器改造与应用

为解决DG260-9.81/540-1型循环流化床锅炉尾部受热面积灰严重,造成排烟温度升高,锅炉热效率降低。公司将原有的声波吹灰器改造成脉冲吹灰器,改造后,锅炉尾部受热面积灰情况明显改观,锅炉排烟温度低于设计值,对同类型循环流化床锅炉吹灰器的选用有一定的借鉴作用。     

蒸汽吹灰器在燃气——蒸汽联合循环电厂余热锅炉中的应用

本文针对燃气－－蒸汽联合循环电厂余热锅炉的积灰问题,提出了几种解决办法,并重点介绍了蒸汽吹灰器用于燃气－－蒸汽联合循环余热锅炉除灰的成功经验。     

垃圾焚烧炉脉冲吹灰器腐蚀失效的机理分析及防范措施

文中通过对一起垃圾焚烧炉脉冲吹灰器腐蚀失效事故的原因分析,阐明的脉冲吹灰器产生腐蚀的机理,提出了在应用此类吹灰器时应注意的相关问题以及相应的防范措施,有效的控制了锅炉尾部受热面的积灰,为锅炉安全稳定运行提供了很好的借鉴经验。     

燃煤电站锅炉的吹灰策略研究

在实现锅炉受热面污染在线监测和熵产在线分析的基础上,从保证锅炉安全稳定运行和实现吹灰收益最大化的角度出发,提出了制定吹灰策略所要遵循的基本原则.根据这些基本原则和锅炉机组的实际运行特性,制定了优化吹灰策略,并建立了3种适合于不同受热面的吹灰模式将优化吹灰策略用于燃煤电站锅炉计算机监测系统上,改变了原来定时吹灰方式,实现了锅炉各主要受热面的优化吹灰.     

锅炉各受热面吹灰作用的对比研究

为优化运行性能，通过清洁因子变化对锅炉主要运行参数影响的性能计算，得到了锅炉不同部位受热面的吹灰作用种类和大小，可作为现场指导吹灰优化运行的依据。不同部位受热面的吹灰作用因受热面位置、受热面种类和大小的不同而异，其重要性也不同。位于烟气流程起始点和蒸汽流程终点的受热面是吹灰优化运行的重点。图13表3参3     

基于神经网络的锅炉对流受热面灰污监测研究

采用多层前向型神经网络,对电站锅炉对流受热面的实时污染状况建立了监测模型。模型选取合适的参数组成输入向量,利用电站数据采集系统下载的实时机组数据,经规格化处理后对神经网络进行训练。结果表明,训练后的神经网络可以较准确地实现锅炉对流受热面的积灰状态的在线监测,为吹灰方案的最优化打下了良好的基础。     

MICROSCALE THERMAL RELAXATION DURING ACOUSTIC PROPAGATION IN AEROGEL AND OTHER POROUS MEDIA

The longitudinal acoustic velocity in silica aerogel is presented as a function of the interstitial gas type and pressure. This was measured using air-coupled ultrasonic transducers configured for differential pulse transit time measurements. The results are interpreted in terms of the thermal relaxation of the acoustic pulse. The microscale temperature oscillations of the gas and solid phases of the aerogel due to the acoustic pulse are not identical if the rate of heat transfer between the two phases is slow compared to the period of the acoustic oscillation. The energy transferred from the gas to the solid phase is lost to the acoustic propagation and, thus, reduces the amplitude and velocity of the acoustic wave. The gas type and pressure may provide independent variables for probing these effects in aerogel.     

CFD analysis of high frequency miniature pulse tube refrigerators for space applications with thermal non-equilibrium model

High frequency, miniature, pulse tube cryocoolers are extensively used in space applications because of their simplicity. Parametric studies of inertance type pulse tube cooler are performed with different length-to-diameter ratios of the pulse tube with the help of the FLUENT^® package. The local thermal non-equilibrium of the gas and the matrix is taken into account for the modeling of porous zones, in addition to the wall thickness of the components. Dynamic characteristics and the actual mechanism of energy transfer in pulse are examined with the help of the pulse tube wall time constant. The heat interaction between pulse tube wall and the oscillating gas, leading to surface heat pumping, is quantified. The axial heat conduction is found to reduce the performance of the pulse tube refrigerator. The thermal non-equilibrium predicts a higher cold heat exchanger temperature compared to thermal equilibrium. The pressure drop through the porous medium has a strong non-linear effect due to the dominating influence of Forchheimer term over that of the linear Darcy term at high operating frequencies. The phase angle relationships among the pressure, temperature and the mass flow rate in the porous zones are also important in determining the performance of pulse tube refrigerator.     

Numerical simulation of a two‐stage pulse tube refrigerator based on adiabatic model

Cryocoolers are devices that are capable of achieving and maintaining cryogenic temperatures for a number of applications such as high‐energy physics, cooling of superconducting magnets, sensors, high‐vacuum production, cryotronics, cryonics, and so on. All the above applications need coolers with high reliability, efficiency, low maintenance, and low cost. The absence of moving parts at the cryogenic temperatures makes the pulse tube (PT) coolers quite suitable for the above applications. In spite of considerable developments in the area of PT cryocoolers, many of the fundamental processes responsible for the cold production are not fully understood. In this work, we present the results of numerical simulations of two‐stage pulse tube refrigerators (PTR) using adiabatic flow of gas through the pulse tube system. A two‐stage PTR is the improved version of single‐stage system to achieve temperature close to 4 K. Assuming adiabatic gas flow through PTs, the algebraic equations for pressure, mass flow, and volumes at different locations have been derived and solved by a MATLAB based program. Using the above, the performance of PTR has been optimized for different operational parameters. The cooling powers predicted by the model have been compared with the experimental data, and they are in good agreement with each other.     

Furnace water-wall slag deposition testing in a 0.5 MWt combustion pilot plant

This article presents combustion pilot-plant test results obtained using newly developed ash deposition probes (ADPs) designed to measure both the thermal and mechanical properties of furnace ash deposits. The ADP measurements are obtained at multiple elevations in the furnace to provide detailed heat absorption and ash deposition time constant profiles for 8 h soot-blowing cycles. Profiles of incident radiation are also presented. Results are presented for four different coal types representing major steam-coal-producing regions in the United States. The furnace heat absorption profiles are distinctly different for each coal type and also vary significantly with furnace elevation. Combined furnace heat absorption and time constant data are used to recommend optimal use of soot-blowing resources, or to specify soot blower and water-wall surface addition and location according to coal type.     

Numerical simulation of laser-induced detonation in mixture of hydrogen with suspended metal particles

Simulation of interaction of laser pulse with gas–particle mixtures plays an important role in environmental and engineering applications. The injection of metal particles with low evaporation temperature and ionization potential causes optical breakdown on individual particle, and leads to drop of detonation minimum pulse energy in the mixture. The mathematical models and numerical methodology for computer modelling of optical breakdown and laser-induced detonation in gas–particle mixture are developed. Sub-models of optical breakdown on metal particle include heating of particle to boiling temperature, formation of vapour aureole around the particle, ionization of vapour aureole and development of electron avalanche, appearance of micro-plasma spots and their expansion, propagation of shock wave in the volume occupied by the particle. Laser-induced detonation in the mixture of hydrogen with flake aluminium particles is simulated based on Eulerian approach, and minimum pure energy of detonation is calculated for different parameters of laser pulse, mass fractions of particles and compositions of gas mixture.     

Successive laser-induced breakdowns in atmospheric pressure air and premixed ethane–air mixtures

Two successive focused laser pulses are employed to experimentally simulate laser-induced breakdown plasmas at high repetition rates. We find that energy absorption of the second laser pulse by the plasma produced by the first laser pulse is enhanced slightly when the time interval between the pulses is shorter than several tens of nanoseconds but falls to almost zero when the time interval is between a few hundreds of nanoseconds and several tens of microseconds. This behavior is attributed to gas heating by the first breakdown event. In premixed ethane–air mixtures, we identify another strong reduction in the second laser pulse absorption when this pulse coincides with the heat released by combustion, typically milliseconds after the first laser pulse. The fuel–air equivalence ratio (?) and base flow speed are also varied in this study. The results show that the window of reduced absorption coinciding with heat release due to combustion is narrowed when the base flow speed is increased, and also under fuel lean and fuel rich conditions. These results suggest that the use of pulsed high frequency laser breakdowns for premixed combustion stabilization is optimized when laser pulse repetition rates below a certain frequency (e.g., 500 Hz at the conditions that ? is 1 and the base flow speed is 4.9 m/s) to maximize laser energy coupling and for improved anchoring of the flame base.     

陶瓷过滤器脉冲清灰系统的性能测定与分析

在由3根滤管组成的高温陶瓷过滤器实验装置上,测定了不同过滤气体温度下滤管脉冲反吹系统的循环性能．比较不同直径的喷嘴在不同脉冲宽度和反吹温度下的气体耗量,利用加尘实验得出各操作参数对过滤循环稳定性和清灰性能的影响规律．实验结果表明,喷嘴每次反吹的气体消耗量与脉冲宽度近似呈线性关系；适当增大喷嘴直径能提高清灰效果,延长反吹周期,但气体消耗量也随之增加．利用已建立的脉冲反吹系统动态模型,对脉冲反吹系统进行了模拟计算,得出了脉冲反吹系统的储气罐容积、管线直径对反吹气体流量和气体消耗量的影响规律．这些结果可用于高温陶瓷过滤器的工程设计和脉冲反吹系统的优化．